Seed germination and seedling survival traits of invasive and non-invasive congeneric Ruellia species (Acanthaceae) in Yucatan, Mexico

We compared requirements for seed germination and seedling establishment for Ruellia nudiflora, an invasive species in Yucatan, Mexico with those of the congeneric non-invasive R. pereducta. Germination and seedling survival rates were higher for R. nudiflora than for R. pereducta under high light. Additionally, the ranges of temperature and water potential that allow germination for R. nudiflora were much broader than those of R. pereducta. Seedlings of R. nudiflora exhibited higher survival to drought by shedding their leaves during drought, an important strategy in environments under extreme drought. Seedlings of R. nudiflora also exhibited higher extreme temperature tolerance than R. pereducta seedlings. Overall, traits exhibited by R. nudiflora such as ability to germinate under a wide range of conditions, adaptation to environmental stress and high tolerance to environmental heterogeneity during the seedling stage, have been repeatedly recognized as determinants of colonization success of invasive species in open disturbed areas.